Food-reinforced key-pecking of pigeons will be studied when each of several response dimensions is under discriminative control of a different dimension of stimuli. Consider pecking on a 2-by-2 square array of keys where response dimensions left-right, top-bottom, and high-versus-low rate are respectively occasioned by the stimulus dimensions circle-triangle, red-green, and singular-plural. After all combinations but single-green-triangle have been trained, will the pigeon peck the bottom right key at a low rate given this novel stimulus combination? If so, will such responding continue only if it is reinforced? The issues are relevant to defining behavior classes (as in generalized imitation) but are also analogous to those of language productivity (as in novel utterances and metaphor). Sequential structure will also be examined. In the 2-by-2 array, suppose contingencies establish top-key pecking followed by bottom-key pecking, with form controlling top left-right pecking and color controlling bottom left-right pecking. If high- and low-rate top-key pecking is then brought under the control of plurality, what happens to bottom-key rates of pecking? (In an analogous human case, voicing of plural "s" depends on voicing of the preceding consonant, as in "dogs" versus "cats".) These and other experiments proposed for studying behavior structure have parallels in the analysis of language structure or syntax. The point is not to argue that these performances would constitute language in the pigeon, but rather to show how structural properties assumed peculiar to language can arise naturally from more fundamental properties of behavior. Understanding such properties is a prerequisite for extending behavior analysis to other issues that are properly more exclusive to the language domain (e.g., problems of semantics and of autoclitic processes).